In triangle `ABC, /_C = (2pi)/3` then the value of `cos^2 A + cos^2 B - cos A.cos B` is equal

If A + B+ C = 3 pi//2 , then the value of cos 2 A + cos 2 B + cos2 C is equal to

Value of cos^2(A - B) + cos^2 B - 2 cos (A-B) cos Acos B is:

In any triangle ABC, the valur of a (cos ^(2) B+ cos ^(2)C)+ cos A (b cos B+ c cos C) is-

If A,B,C are the angles of triangle ABC, then the minimum value of |{:(-2,cos C , cos B),(cos C , -1, cos A ) , (cos B , cos A , -1):}| is equal to :

If A,B,C are the angles of triangle ABC, then the minimum value of |{:(-2,cos C , cos B),(cos C , -1, cos A ) , (cos B , cos A , -1):}| is equal to :

In a Delta ABC, the value of (a cos A+b cos B+c cos C)/(a+b+c) is equal to

If ABC is a right angled triangle, then the value of (cos ^(2)A +cos ^(2) B+ cos ^(2)C) is -

ABC is a right angled triangle with angleA=90^(@) .Then the value of cos^(2)A+cos^(2)B+cos^(2)C is :

In a Delta ABC,a=5,b=3 and c=7, then the value of 3cos C+7cos B is equal to

In triangle ABC , a (b^2 +c^2 ) cos A + b (c^2 +a^2 ) cos B + c(a^2 +b^2 ) cos C is equal to